As with most things in life, a little bit of knowledge and the right tools for the job can make things seem infinitely easier. In this case a little bit of reading can save you untold frustration and money.

There can be a lot of variables in getting a pulsejet to run for the first time, and when using equipment that is not ideal the procedure can be further complicated. The two biggest factors that are commonly a problem are Air Source & Delivery, and the Ignition System.

Air Source & Delivery

Most pulsejets need a bit of air blown into them to start up. The most convenient method is usually a portable air compressor, since you can fill it up and then take it places where AC power is not available. It is important to get a compressor that can provide enough to start stubborn engines, that way you’re not constantly sitting around waiting for it to recharge.

Despite all that, the blowgun nozzle is more important in my opinion. Most compact blow nozzles have little control as far as easing it on, when you press down on the lever it breaks resistance and all of a sudden pops on with its maximum airflow. This can make it very difficult to fine tune your airflow or just give the engine light puffs of air, which is typically the single most important factor in starting an engine.

A well designed engine can start over a wide throttle range as long as you’re able to provide it just the right amount of air. The fuel and air need to be mixed in a certain ratio in order to burn. A blowgun nozzle that effectively only provides one level of air means that there is only going to be one point where the engine will start, assuming that air flow falls within the range the engine can run at.

The typical procedure would be to turn on your ignition source, begin blowing air into the engine, and open the fuel valve. If things go well, the engine will start when the fuel flow reaches the proper rate to burn at the set air flow. If it doesn’t start up, something is likely out of range. Without the right nozzle you’ll have to try varying the air pressure from the regulator, or change the distance of the nozzle from the engines intake which is slow and introduces more variables to try to troubleshoot.

ch blow nozzle

The ideal air blow gun nozzles have a bent tube which also puts your hand out of the line of fire from the engines intake, and a long squeeze grip that gives you fine control over airflow and allows you to ease into things.

If the engine does not start up you can instantly change the air flow by squeezing less or more, and see which makes the engine seem more likely to start.

By being able to rapidly change the air flow from very low to very high, while also being able to actuate the fuel valve on and off, you can quickly find where the engine wants to run in sporadic bursts, and then isolate that range of inputs until you are able to get it started.

For the money the Campbell Hausfeld pistol grip blow nozzle can’t be beat, and only costs about $6 on Amazon.

Ignition System

Deciding on your ignition system can be a little overwhelming. There are a lot of options available but few really good ones. Ideally you want something that provides a lot of sparks per second. The more sparks per second the more likely the engine will light up right as it reaches the proper fuel air flow ratio. You don’t need an extremely hot spark either. High voltage transformers from tv’s, microwaves, and neon signs all can be very lethal and shouldn’t even be thought of when planning your ignition system.

One option is a Model T Ford Buzz Coil; there’s only one manufacturer still making them, and they aren’t cheap or light. Another option is getting a cheap car ignition coil and setting up an ignition relay circuit; this is way more complicated and the circuit components tend to burn out quickly. There is another option using a car ignition coil, a piece of spring steel or reed switch, and winding a small electromagnet; basically you’re building your own modern day Model T Ford Buzz Coil. This can actually be a fun and rewarding project of its own, and has great long term reliability. However, the choice that gives you the best bang for your buck, is a simple AA battery powered BBQ grill ignitor.

bbq grill ignitor

The grill ignition unit is cheap, very small, and provides about 6-8 sparks a second with a well charged AA battery. Lithium batteries work fantastic and last a long time. The spark rate is more than useable, and you cant beat the size, price or power requirements. At very least you should have one as a backup to your larger more complicated ignition system, or just to have for a portable demonstration rig.
It also has two outputs if you need to provide sparks to more than one spark plug simultaneously and has plenty of power to fire across wide spark gaps, meaning you can open your spark plug up more and have better ignition. This model is a reliable brand and can be found on Amazon for about $17. Stores like home depot sell them for around $30. While it is weather resistant, ideally it should be kept indoors for best long term reliability.

 

 

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